Lifting-jack



' no Model.) V

' AULT.

' ING JACK. No. 574,371. I Patented Jan. 5, 1897.

HZZ/ESL IHVEHZFL UNITED STATES ATENT OFFICE.

THOMAS B. AULT, OF KNOXVILLE, TENNESSEE.

LlFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 574,371, dated January 5, 1897.

Application filed June 25,1896- To all whom it may concern:

Be it known that I, THOMAS B. AULT, a citizen of the United States, residing at Knoxville, county of Knox, and State of Tennessee, have invented certain new and useful Improvements in Lifting-Jacks; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

This invention relates to lifting-jacks, and has for its object to provide a simple, durable, and inexpensive lifting-jack wherein the load lifted operates to positively lock the parts in their elevated positions.

To these ends my invention consists in the combination and arrangement of parts hereinafter fully described, and definitely pointed out in the claim following the description, reference being had to the accompanying drawings, forming a part of this specification, wherein- Figure 1 is a perspective View of my improved lifting-jack, illustrating it in its lowered position. Fig. 2 is a side elevation thereof, the parts being shown in the same position as in Fig. l and Fig. 3 is a similar view showing the jack in its raised position.

Referring to the drawings, the referenceletter P indicates the base of the lifting-jack, from the opposite ends of which rise fixed vertical standards 0 and D. To the standard O is pivoted at K one end of a notched lifting-bar A, the length of which is somewhat less than the distance between the standards C and D. To the standard D is pivoted at H one end of alever E, and said lever near its pivoted end is provided with a lateral projection n, which projects to one side of the lever toward the standard 0. Two links B B are pivoted at their lower ends at G to the projection n, and at their opposite ends are pivoted to the end of the leverA at L.

The operation of my improved lifting-jack Serial No. 596,900. (No model.)

is as follows: The pivotal connection G between the lever E and links B B being at a point intermediate the pivoted end and free end of the lever E, the lower ends of the links B B, when the lever E is in its lowered position, will be thrown to the outer side of the vertical center of the standard D. The load to be lifted is caused to engage one of the notches min the lifting-bar A, when, by lifting the lever E, owing to the fact that the length of the lifting-bar A is less than the distance between the standards 0 D, the lever E will be thrown past the vertical center of the standard D, and as the links B B are pivoted to the projection n, formed on the inner side of the lever E, the latter, when it passes the vertical center, will be thrown by the weight of the load still farther past the vertical center until the upper end of the lever abuts the end of the lifting-bar A, when the jack will be locked and held locked with the load in its elevated position. When the parts are in this position, the lever E will rest in an inclined position against the end of the lifting-bar A, so that the tendency of the load is to maintain the parts locked effectually against accidental displacement.

Having described my invention, what I claim is- In a lifting-jack, the combination with the base P, provided with vertical uprights O, D, at its opposite ends, of the lever E, pivoted at its lower end to the standard D, and provided on its inner side intermediate its pivoted end and free end with an inwardly-projecting projection 01, a notched lifting-bar A pivoted at one end to the standard 0, and links B, B pivoted at their upper ends to the other end of the bar A and at their lower ends pivoted to the projection n, the length of the lifting-bar A being less than the distance between the standards O, and D, substantially as described and for the purpose specified.

THOMAS E. AULT.

Attest:

L. J. PETERS, W. O. LAWSON. 

